Plated material and plating pretreatment method

ABSTRACT

A plated material containing a base material and a metal plating that covers the base material, the base material containing a main raw material free of any carbon materials, and a carbon material that is present inside the main raw material. A plating pretreatment method including a first step of preparing a base material from a main raw material free of any carbon materials and a carbon material, the base material containing the main raw material and the carbon material that is present inside the main raw material; and a second step of charging the base material into a treatment tank, and immersing the base material in a supercritical fluid or subcritical fluid containing an organometallic complex of palladium in the treatment tank.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2022-098321 filed on Jun. 17, 2022, the contents of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a plated material and a plating pretreatment method.

BACKGROUND ART

In the related art, there has been proposed a plated material in which a base material such as a fiber is applied with a metal plating. In addition, in order to obtain such a plated material, there has also been proposed a plating pretreatment method in which a base material is immersed in a supercritical fluid or subcritical fluid containing an organometallic complex of a plating catalyst metal to adhere the organometallic complex to the surface of the base material (for example, JP2007-56287A, JP2010-70826A, and JP2010-106316A). According to this plating pretreatment method, when the organometallic complex adheres to the surface of the base material, a metal plating can be applied to the base material in a subsequent electroless plating step or the like.

SUMMARY OF INVENTION Technical Problem

However, when electroless plating is performed after the plating pretreatment method described in JP2007-56287A, JP2010-70826A, and JP2010-106316A, the plating depositability has never been high. Therefore, the plating treatment takes a long time, and the production takes a long time, resulting in a cost increase. In addition, since the plating depositability is not high, there is a concern that the base material may be immersed in a plating liquid for a long time, and the strength of the base material may be deteriorated.

The present disclosure has been made to solve such problems in the related art, an object thereof is to provide a plated material and a plating pretreatment method that can prevent a cost increase and deterioration of the strength of a base material.

Solution to Problem

A plated material according to the present disclosure is a plated material containing: a base material; and a metal plating that covers the base material, in which the base material contains a main raw material free of any carbon materials, and a carbon material that is present inside the main raw material.

In addition, a plating pretreatment method according to the present disclosure includes: a first step of preparing a base material from a main raw material free of any carbon materials and a carbon material, the base material containing the main raw material and the carbon material that is present inside the main raw material; and a second step of charging the base material into a treatment tank, and immersing the base material in a supercritical fluid or subcritical fluid containing an organometallic complex of palladium in the treatment tank.

Advantageous Effects of Invention

According to the present disclosure, it is possible to provide a plated material and a plating pretreatment method that can prevent a cost increase and deterioration of the strength of a base material.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a cross-sectional view showing a plated fiber, which is an example of a plated material according to an embodiment of the present disclosure.

FIG. 2 is a partially enlarged view of the fiber shown in FIG. 1 (before plating), and shows a photograph taken by a transmission electron microscope (TEM).

FIG. 3 is a partially enlarged view of a fiber according to a comparative example, and shows a photograph taken by a transmission electron microscope (TEM).

FIG. 4 is a process diagram showing a method for producing a plated fiber according to the present embodiment.

FIG. 5 is a table showing Example and Comparative Examples.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present disclosure will be described in accordance with a preferred embodiment. Note that the present disclosure is not limited to the embodiment shown below, and can be appropriately modified without departing from the gist of the present disclosure. In the following embodiment, a part of configurations may be not described or shown in the drawings, and regarding details of the omitted techniques, publicly known or well-known techniques are appropriately applied as long as there is no contradiction with contents described below.

FIG. 1 is a cross-sectional view showing a plated fiber, which is an example of a plated material according to an embodiment of the present disclosure. A plated fiber (plated material) 1 shown in FIG. 1 contains a fiber (base material) 10 and a metal plating 20 that covers the fiber 10.

The fiber 10 contains a main raw material 11 and carbon material 12 incorporated into the main raw material 11. The main raw material 11 is free of any carbon materials, such as a PET (polyethylene terephthalate) resin. This fiber 10 is produced from a resin in which the carbon material 12 is kneaded into the main raw material 11. Accordingly, the fiber 10 in which the carbon material 12 is present inside the main raw material 11 is obtained. Note that the content of the carbon material 12 is preferably 0.1% or more and 3.0% or less, and more preferably 0.6% or more and 2.0% or less, with respect to the entire fiber 10. The main raw material 11 is not limited to a PET resin, and may be composed of a polypropylene, a nylon, a polyarylate, or the like. The main raw material may contain carbon materials at an impurity level (more specifically, in a total amount of 1% or less with respect to the weight of the main raw material) as long as the function of the main raw material is not impaired, and such a main raw material containing carbon materials at an impurity level falls within the meaning/scope of the main raw material 11 free of any carbon materials. Examples of the carbon material 12 include a carbon black. The carbon black may be kneaded into a raw material as black pigment, reinforcement or conductive material.

The metal plating 20 is a conductive metal plating formed on the fiber 10, for example, by an electroless plating treatment using a chemical reaction. This metal plating 20 is made of one or more metals selected from the group consisting of copper, silver, gold, nickel, chromium, tin, zinc, palladium, rhodium, ruthenium, antimony, bismuth, germanium, cadmium, cobalt, and indium.

The plated fiber 1 contains palladium as a plating catalyst metal for depositing the metal plating 20 by a chemical reaction. As shown in FIG. 1 , this palladium is in a state of adhering to the surface and the vicinity of the surface of the fiber 10 by immersing the fiber in a supercritical fluid or subcritical fluid (in, for example, supercritical carbon dioxide) containing an organometallic complex of palladium. Further, in the present embodiment, palladium also agglomerates around the carbon material 12 forming the fiber 10, as shown in FIG. 1 .

FIG. 2 is a partially enlarged view of the fiber 10 shown in FIG. 1 (before plating), and shows a photograph taken by a transmission electron microscope (TEM). Note that small black dots in FIG. 2 indicate palladium. FIG. 2 shows the inside of a fiber 10 in which a PET resin is used as the main raw material 11 and the carbon material 12 is kneaded therein. As shown in FIG. 2 , the carbon material 12 is in a state of being dispersed in the fiber 10.

Here, the present inventors have found that palladium has the property of agglomerating in the vicinity of the carbon material 12. Therefore, as shown in FIG. 2 , palladium agglomerates in the vicinity of the carbon material 12 present inside the fiber 10. That is, in the present embodiment, palladium is in a state of being distributed not only on the surface of the fiber 10 but also inside the fiber 10. As a result, a large amount of palladium adheres to the fiber 10, and the metal plating 20 is easily deposited on the fiber 10 in a subsequent electroless plating treatment.

FIG. 3 is a partially enlarged view of a fiber according to a comparative example, and shows a photograph taken by a transmission electron microscope (TEM). The fiber shown in FIG. 3 is free of any carbon materials. Therefore, in the comparative example, palladium (white dots in FIG. 3 ) is dispersed in the vicinity of the surface of the fiber.

FIG. 4 is a process diagram showing a method for producing the plated fiber 1 according to the present embodiment. Note that steps S1 to S3 shown in FIG. 4 indicate a plating pretreatment method.

First, a fiber production step is performed (S1: first step). In the fiber production step, a fiber 10 is produced from a raw material containing a main raw material 11 free of any carbon materials and carbon material 12 incorporated into the main raw material 11.

Then, an immersion step is performed (S2: second step). In the immersion step, a bundle of fibers 10 is charged into a treatment tank (not shown), and the bundle of fibers 10 is immersed in a supercritical fluid or subcritical fluid (in, for example, supercritical carbon dioxide) containing an organometallic complex of palladium. With this step, the organometallic complex of palladium adheres to the vicinity of the surface of the fiber 10 and agglomerates around the carbon material 12 inside the fiber 10.

Thereafter, an electroless plating step is performed (S3). In the electroless plating step, the fiber 10 that has undergone a reduction step is continuously supplied to an electroless plating tank, and a metal plating 20 is deposited around the palladium using a chemical reaction. With above, the plated fiber 1 is obtained.

Next, Example and Comparative Examples will be described. FIG. 5 is a chart showing Example and Comparative Examples.

A plated fiber according to Example is produced through an immersion step, a reduction step, and an electroless plating step on a plurality of types of fibers having various values of carbon material content of 0.1% or more and 3.0% or less. A plated fiber according to Comparative Example 1 is produced through an immersion step, a reduction step, and an electroless plating step on fibers having a carbon material content of 0% (fibers produced only from the main raw material in Example). A plated fiber according to Comparative Example 2 is produced through an immersion step, a reduction step, and an electroless plating step on carbon fibers (carbon material content: 100%).

Note that conditions for the immersion step are that the fibers 10 is charged into a treatment tank and immersed in a supercritical fluid or subcritical fluid (in, for example, supercritical carbon dioxide) containing an organometallic complex of a plating catalyst metal. This time, the base material was immersed in supercritical carbon dioxide at conditions of 130° C. and 15 MPa for 30 minutes. Further, the electroless plating step was performed in a formalin bath, which was a common electroless copper plating method (copper concentration: 2.5 g/L, NaOH concentration: 8.0 g/L, formalin concentration: 3.0 g/L).

Evaluation was made regarding the plating depositability in the production process (electroless plating step) of the plated fibers according to Example and Comparative Examples 1 and 2, and the external appearance (finish) and the plating physical properties after the production.

First, regarding the plating depositability, a plating reaction occurred in about 30 seconds in Example, resulting in a fast plating reaction. In contrast, in Comparative Example 1, the plating reaction did not start even after 10 minutes, resulting in a very slow plating reaction. In addition, in Comparative Example 2, the plating reaction occurred immediately after immersion in the plating liquid, resulting in a very fast plating reaction.

From the above, the plating depositability was good in Example and Comparative Example 2, but not good in Comparative Example 1.

In addition, as a result of confirming the external appearance, in Example and Comparative Example 2, the entire fiber (base material) was applied with a plating, and the overall finish had a metallic luster. In contrast, in Comparative Example 1, the color of the plating was poor and the plating was sparse. Therefore, the external appearance was good in Example and Comparative Example 2, but not good in Comparative Example 1.

Further, as a result of confirming the plating physical properties (performance as a plated fiber), no deterioration in physical properties of the fiber (base material) was confirmed, no peeling of the plating was confirmed, and the adhesion of the plating was good in Example. In contrast, in Comparative Example 1, a long immersion time in the plating liquid resulted in deterioration in strength of the fiber (base material), and the sparse plating made it difficult to use as a conductor. In addition, in Comparative Example 2, the plating reaction was too fast, a large amount of hydrogen accompanied by the plating reaction was deposited, and the plating adhesion is slightly lowered. In particular, when the carbon fibers were continuously supplied to the plating tank and wound up, the plating was partially peeled off. Further, an excessive plating may be deposited between bundles of carbon fibers (between fibers), and the excessively deposited metal plating may be peeled off in a post-step. Therefore, there is a possibility that a short circuit or the like may occur due to the peeled-off metal plating.

From the above, it is confirmed that a carbon material content of 0.1% or more and 3.0% or less is favorable.

In this way, according to the plated fiber 1 and the plating pretreatment method of the present embodiment, the fiber 10 contains the main raw material 11 and the carbon material 12 incorporated into the main raw material 11. Here, the present inventors have found that the organometallic complex of palladium easily adheres to the carbon material 12 when the fiber 10 is immersed in a supercritical fluid or subcritical fluid containing the organometallic complex of palladium. Therefore, palladium can agglomerate in the vicinity of the carbon material 12 in the fiber 10 by incorporating the carbon material 12 into the main raw material 11 free of any carbon materials. Since palladium agglomerates to the inside of the fiber 10 and the amount of palladium adhering to the fiber 10 increases, it does not take much time in the post-step of providing the metal plating, and it is possible to prevent the strength of the fiber from being deteriorated by immersing in the plating liquid for a long time. Therefore, it is possible to provide the plated fiber 1 that can prevent a cost increase and deterioration of the strength of the fiber.

Note that since palladium agglomerates in the vicinity of the carbon material 12, the metal plating 20 is easily formed inside the fiber 10. As a result, the adhesion of the metal plating 20 tends to be good.

Since the weight proportion of the carbon material 12 to the entire fiber 10 is 0.1% or more, the time for immersion in the plating liquid can be efficiently shortened. In addition, since the weight proportion of the carbon material 12 is 3.0% or less, it is possible to prevent the plating from peeling off due to too much carbon material 12.

Although the present disclosure has been described above based on the embodiment, the present disclosure is not limited to the above embodiment, and modifications may be made without departing from the gist of the present disclosure and publicly known or well-known techniques may be appropriately combined.

For example, the plated fiber 1 in which the metal plating 20 is applied to the fiber has been described in the above embodiment, but an object to which the metal plating 20 is applied is not limited to the fiber 10, and may be another base material. 

What is claimed is:
 1. A plated material comprising: a base material; and a metal plating that covers the base material, wherein the base material contains a main raw material free of any carbon materials, and a carbon material that is present inside the main raw material.
 2. The plated material according to claim 1, wherein the carbon material is contained in an amount of 0.1 mass % or more and 3.0 mass % or less with respect to the base material.
 3. A plating pretreatment method comprising: a first step of preparing a base material from a main raw material free of any carbon materials and a carbon material, the base material containing the main raw material and the carbon material that is present inside the main raw material; and a second step of charging the base material into a treatment tank, and immersing the base material in a supercritical fluid or subcritical fluid containing an organometallic complex of palladium in the treatment tank. 